double deductions

I have a policy with them. they deducting double monthly via debit order from my bank account and Cassey n Associates. last year January I called them to resolve the matter and in april they refunded 4 months premiums back. since then to date they been deducting double even though they promised me they will stop Cassey n Associates. so I want them to refund my balance due to me and tell me what I must go and do for me to stop Cassey from deducting the same policy amount. I sent them email on 26th January 2016 and no response to date.